Filter apparatus

ABSTRACT

A filter apparatus having a filter housing ( 1 ), which accommodates at least one filter element ( 17 ) having an inner filter cavity ( 23 ) enclosed by a filter medium ( 27 ), wherein the housing ( 1 ) contains an element holder ( 19 ) which interacts with the filter element ( 17 ) located in the functional position, is characterized in that the element holder ( 19 ) has a projecting accommodating part ( 43 ), of which the outer configuration is adapted to the shape of an opening ( 37 ), which is located at that end of the relevant filter element ( 17 ) which is to be secured to the element holder ( 19 ), such that the accommodating part ( 43 ) fits through the opening ( 37 ) of the filter element ( 17 ) located in the functional position.

The invention relates to a filter apparatus having a filter housing, which accommodates at least one filter element having an inner filter cavity enclosed by a filter medium, wherein the housing contains an element holder that interacts with the filter element, when the filter element is in the functional position. The invention further relater to a filter element that is provided for use inside such a filter apparatus.

Filter devices of this kind are known from the prior art. They are widely used in configurations varying in terms of the structural type, size and/or pressure level thereof, for the filtration of the most varied technical fluids, such as hydraulic fluids, cooling lubricants, fuels, lubricating oils, and the like. Since operating disturbances, which can range as far as to failure of such filter devices, are potentially responsible for damaging or destroying the systems downstream of where the damage occurred and can cause considerable financial damage, the operational reliability of such filter devices is of great importance. Therefore, when operating such filter devices, it must be ensured that, on the one hand, the filtration process is performed using a filter element that is in the ready state and disposed inside the filter housing and, on the other hand, that the specifications of a filter element that is used in this process are precisely matched to the operational requirements of the associated system with regard to the quality of the filter, assignment to the corresponding pressure level, flow resistance and the like.

Therefore, it is the object of the present invention to provide a filter apparatus with increased reliability in order to protect against malfunctions during the filtering process.

According to the invention, this object is achieved with a filter apparatus that has all of the characterizing features as specified in claim 1.

According to the characterizing portion of claim 1, an essential special aspect of the invention lies in the fact that the element holder, which is provided inside the filter housing, includes a projecting accommodating part for securing the respective filter element, and the exterior shape of the projecting accommodating part fits adapted to the shape of an opening that is disposed on the end of the related filter element that must be secured on the accommodating part of the element, such that the accommodating part fits through the opening of the filter element, when the filter element is in the functional position. This way, it is ensured that only such filter elements can be brought in the functional position inside the filter housing that allow for the appropriate projecting accommodating part, which is matched to the shape of the element holder, to fit through the opening. This way, it impossible to avoid the risk that used filter elements are not compliant with the specifications in terms of the filter quality, the permissible pressure level and the like, thereby providing better operational reliability.

In especially advantageous embodiments, the accommodating part of the element holder is disposed such that it extends, when the related filter element is in the functional position thereof, into an accommodating space that is disposed on an allocated end cap and reaches into the inner filter cavity. With this structural design, it is ensured that, were an attempt made at inserting a wrong filter element, a filter element that does not have an accommodating space at the element holder thereof for the accommodating part that extends into the interior of the filter cavity, the insertion movement of the filter element would be blocked prior to reaching the functional position in that the accommodating part would be stopped, and thereby blocked, by the end cap, thus providing the operator with a clear signal that he is attempting to insert the “wrong” filter element.

Preferably, the arrangement is selected such that at least the part of the accommodating part, which is provided for the engagement in the opening of the accommodating space of the filter element, has a shape that is not round.

In especially preferred embodiments, said accommodating part can be configured in the manner of a spike, and the accommodating space on the element holder can be configured in the manner of a dome.

Especially advantageously, the chosen apparatus can provide that the spike has planar surface portions along the circumference thereof that define a cross-section that has the shape of four straight sides that are inscribed in a square, wherein the size of the cross-section of the spike becomes smaller toward the top, free end thereof. Due to the slender, free end of the spike, achieving the engagement with the dome is especially easy and convenient.

Since with the non-round shape of the spike having planar surface portions along the circumference thereof and the corresponding non-round shape of the opening of the accommodating dome a corresponding relative rotational position is required between the filter element and the fore the spike to engage in the accommodating dome, especially preferred embodiments provide for rotatably supporting the spike on a shaft that is disposed on the element holder, which extends into a central bore of the dome. When combining the accommodating dome and the spike, the spike positions itself automatically by means of the more slender free end in the rotary position that is necessary for the combining action.

In especially advantageous embodiments, the shaft has a collar that secures the spike, which rests there against, against any axial movement that is directed away from the respective filter element.

To protect against any lifting action of the spike from the shaft in the other direction, it is possible to provide a snap ring on the shaft that acts in conjunction with a groove disposed in the central bore of the spike, thereby axially securing the same.

The shaft can be screwed into a sealable oil discharge opening of the filter housing, which results in an especially simple and compact structural assembly.

For the oil discharge opening to be able to fulfill its discharge function despite the shaft, which is screwed thereto, the apparatus can be especially advantageously provided with an internal fluid path between the exterior of the collar and the discharge opening of the housing, such that, even when the shaft is screwed in, opening a discharge screw on the discharge opening will allow for a discharge to occur.

Another object of the present invention seeks to provide a filter element for use in a filter apparatus according to any one of the claims 1 to 11, wherein the filter element has characteristics as specified in claim 12.

Further configurations of the filter element are set forth in the subsequent claims 13 to 17.

The invention will be described in further detail below based on an embodiment as represented in the drawing.

Shown are as follows:

FIG. 1 is a perspective view of an embodiment of the filter apparatus according to the invention, drawn as partially cut open;

FIG. 2 is a depiction similar to the one in FIG. 1, wherein the embodiment according to the invention as shown in FIG. 1 is installed inside a filter housing of a common structural type;

FIG. 3 is a greatly enlarged exploded view, from a slanted perspective, showing only the end cap of the filter element and the element holder of the filter housing according to the embodiment from FIG. 1;

FIGS. 4 and 5 are side and longitudinal views, respectively, of a shaft of the element holder from FIG. 3;

FIGS. 6 and 7 are longitudinal and top views, respectively, of only one spike serving as the accommodating part for the element holder from FIG. 3; and

FIGS. 8 and 9 are slanted perspective views of only the end cap of the filter element, seen from the bottom and/or top sides.

FIG. 1 shows an embodiment of the filter apparatus according to the invention that is provided for the filtration of pressurized fluids. The filter housing 1, which defines a vertical axis 3, includes a cylindrical main part 5 that has a head part 7 screwed to the top end thereof. At the bottom end, the main part 5 is closed, except for a discharge opening 9, and a discharge screw 11 is screwed into the internal thread of said discharge opening. The top head part 7 includes a connection 13 for inflowing unfiltered fluid and a connection 15 for the filtrate outlet. Fluid paths that are disposed within the head part 7 and that correspond to the pertinent prior art, which is why they are not depicted in further detail, connect the connection 13 and 15 to the untreated side and the clean side of the respective filter element 17 that is retained inside the housing 1, wherein a bypass means inside the head part 7 creates a secondary closure, if necessary, also corresponding to the prior art.

The filter housing 1 is cut open in the drawing along the longitudinal axis 3 such that the exterior of the filter element 17 is visible, wherein the same is also depicted as cut open in a bottom longitudinal section, by which the filter element 17 is mounted in an element holder 19 on the floor 21 of the filter housing 1. This opens up a view to the inside upon the filter cavity 23 that is coaxially disposed relative to the vertical axis 3 and surrounded by a fluid-permeable support pipe 25, upon which, in turn, there is disposed a filter medium 27 that constitutes a hollow cylinder. During the filtration process, said filter medium receives the flow-through from the exterior, which constitutes the untreated side 29, toward the filter cavity 23, which constitutes the clean side.

Further details of the element holder 19 of the filter housing 1, which serves to secure the filter element 17 in the functional position thereof, as shown in FIG. 1, and that interacts with an end cap 31 of the filter element 17, can be derived more clearly from FIGS. 3 to 9. The end cap 31 includes a projecting rim 33, as known from the prior art, that is allocated to the end region of the filter medium 27 framing the same. An essential difference in contrast to common end caps presently lies in the fact that the end cap 31 includes a body, which is provided as a component fashioned in one piece therewith, that is centrally disposed, extending along the vertical axis 3 into the interior of the filter element 17, and which has the shape of an inverted goblet or a dome 35 and tapered from the end-side opening 37 thereof (see particularly FIG. 8) toward the internal end, such that the dome 35 constitutes an internal accommodating space 39 in the manner of a sleeve, which is also tapered toward the internal end. An opening of the accommodating space 39 that is disposed at the internal end can be sealed by a screw 41. Instead of the screw 41, the use of a plug, preferably manufactured of a sintered metal, is also possible, which can be driven into the corresponding opening. The aforementioned sintered metal material has a certain degree of porousness, whereby it is possible to achieve a pressure equalization with the closure plug placed on the filter element, while also achieving a kind of a small filter that is able, when it is disposed inside the filter, to separate even the finest particle impurities. To this end, the closure screw 41 could also be made of a sintered metal material with a predefinable porousness.

The element holder 19 includes an accommodating part in the shape of a spike 43, which is accommodated inside the accommodating space 39 of the dome 35, when the filter element 17 is in the functional position thereof. As can be derived from FIGS. 3, 6 and 7, the spike 43 has a non-round shape, wherein planar surface parts 45 are provided along the circumference of the spike 43 in the longitudinal section that engages in the accommodating space 39, whereby there results a cross-section of the spike 43 with four straight edges 47, which are inscribed inside a square, see FIG. 7. These planar surface parts 45 converge toward the end 49 in a manner that corresponds to the tapering of the accommodating space 39, such that, when the spike 43 is accommodated inside the accommodating space 39, the interior surfaces 51 of the dome 35 fit against the planar surface parts 45 of the spike 43. The longitudinal ribs 53 (not all of which are identified by reference numerals in the drawings) extend along the exterior of the dome 35, and are disposed with a spacing there between, ranging from a collar 55, which is provided as a stop for the support pipe 25, toward the internal end of the dome 35.

As can be derived from FIGS. 3, 6 and 7, the spike 43 includes rounded connecting surfaces 57 between the planar surface parts 45, as well as radially projecting flange parts 59 on two opposing sides. A central bore 61 extends inside the spike 43 from the thicker bottom end thereof to a compensation bore 63 on the tapered top end 49. The spike 43 is rotatably supported by the central bore 61 thereof on a shaft 65 of the element holder 19. This rotatable support of the spike 43 facilitates moving the non-round spike 43 into the accommodating space 39 of the dome 35, when the filter element 17 is inserted into the filter housing 1, because, due to the tapered shape of the spike 43, the same adjusts itself automatically to the appropriate rotational position when moving into the dome. The shaft 65 includes an external thread 67 on the bottom end thereof, by which it is screwed into the internal thread of the discharge opening 9 of the filter housing 1, wherein a hexagonal insert bit 69 is provided for the screwing action on the top end of the shaft 65. Following the hexagonal insert bit 69 is a circular cylindrical longitudinal section 71 by which the shaft 65 is rotatably supported, fitted in a supporting section 73 of the central bore 61 of the spike 43. The bore 61 includes, as can be seen in FIG. 6, an extension 75 at the bottom end thereof with a groove 77 configured therein. Said groove constitutes, interacting with a snap ring 78, which is only indicated in FIG. 3 and disposed in a groove 79 of the shaft 65, a safety means to protect against any axial movement of the spike 43 in the removal direction from the spike shaft 65. In this regard, the shaft 65 constitutes, together with the spike 43, a structural unit in two parts.

Below the snap ring 78, which is disposed inside the groove 79, the shaft 65 includes a collar 81 that constitutes a radial extension, and which forms a stop surface 83 for securing the spike 43 against any axial downward movement. The collar 81 includes a fluid connection 87 that is disposed between opening 85 on the exterior thereof and the bottom end that can be screwed into the discharge opening 9 of the housing 1, and which allows for emptying the housing 1, after the discharge screw 11 has been removed.

FIG. 2 depicts a situation where a filter element 17 according to the invention, which is provided with an end cap 31 having a dome 35 for forming an accommodating space 39 for a spike 43, as is present as an element holder of a filter apparatus according to the invention, is in the functional position thereof. However, contrary to FIG. 1, in the representation in FIG. 2, the filter element 17 is not inserted into a filter housing 1 according to the invention; instead, it is inserted in a filter housing of a common structural type, which includes a closed floor part 21 without an element holder with a projecting accommodating part in form of a spike disposed thereupon. Therefore, as depicted in FIG. 2, the filter element 17 that is configured according to the invention can also be inserted and brought into the functional position inside such a common filter housing.

In the present embodiment, the element holder 19 is made of steel parts in form of a spike 43 and shaft 65. Preferably, the end cap 31 of the filter element 17 is a die-cast part made of an aluminum/zinc alloy. Alternately, the end cap 31 could also be die-cast from a plastic material. 

1. A filter apparatus having a filter housing (1), which accommodates at least one filter element (17) having an inner filter cavity (23) enclosed by a filter medium (27), wherein the housing (1) contains an element holder (19) that interacts with the filter element (17) when the filter element is in the functional position thereof, characterized in that the element holder (19) has a projecting accommodating part (43), the outer configuration of which is adapted to the shape of an opening (37), which is disposed at the end of the relevant filter element (17) that is to be secured to the element holder(19), such that the accommodating part (43) fits through the opening (37) of the filter element (17) when said filter element is in the functional position thereof.
 2. The filter apparatus according to claim 1, characterized in that the accommodating part (43) of the element holder (19) is disposed such that it extends into an accommodating space (39), which is disposed on an associated end cap (31) allocated thereto, when the respective filter element (17) is in the functional position thereof, extending into the inner filter cavity (23).
 3. The filter apparatus according to claim 1, characterized in that at least the part of the accommodating part (43) that is provided for the engagement in the opening (37) of the accommodating space (39) of the filter element (17) has a non-round circumference.
 4. The filter apparatus according to claim 1, characterized in that the accommodating part is configured in the manner of a spike (43), and in that the accommodating space (39) is configured in the manner of a dome (35).
 5. The filter apparatus according to claim 1, characterized in that the spike (43) includes planar surface parts (45) along the circumference thereof, which define a cross-sectional shape with four straight sides (47) that are inscribed in a square.
 6. The filter apparatus according to claim 1, characterized in that the size of the cross-section of the spike (43) is reduced toward the top free end (49) thereof.
 7. The filter apparatus according to claim 1, characterized in that the spike (43) is rotatably supported on a shaft (65), which is disposed on the element holder (19) and which extends into a central bore (61) of the spike (43).
 8. The filter apparatus according to claim 1, characterized in that the shaft (65) includes a collar (81) that secures the spike (43), which rests against said collar, against any axial movement that is directed away from the respective filter element (17).
 9. The filter apparatus according to claim 1, characterized in that a snap ring (78), which is disposed on the shaft (65), secures the spike (43), acting in conjunction with a groove (77) that is disposed inside the central bore (61) of the spike, against any lift-off action from the shaft (65).
 10. The filter apparatus according to claim 1, characterized in that the shaft (65) is screwed into an oil discharge opening (9) of the filter housing (1) that can be sealed.
 11. The filter apparatus according to claim 1, characterized in that the shaft (65) includes and internal fluid path (87) between the exterior of the collar (81) and the oil discharge opening (9) of the housing (1).
 12. A filter element for use in connection with a filter apparatus according to claim 1 that can be secured on an element holder (19) of a respective filter housing (1) and that includes a filter medium (27) that encloses an inner filter cavity (23), characterized in that, at the end that must be secured to the element holder (19), there is an opening (37) provided, constituting an access to the inner filter cavity, which is adapted to the size and shape of an accommodating part (43) extending away from the element holder (19) such that the accommodating part (43) fits through the opening (37) when the filter element (17) is in the functional position thereof.
 13. The filter apparatus according to claim 12, characterized in that the opening (37) is configured on an end cap (31) that frames the filter medium (27) in such a manner that the accommodating part (43), which extends into the inner filter cavity (23) when in the functional position, fits through the opening (37).
 14. The filter apparatus according to claim 12, characterized in that the end cap (31) includes an accommodating space (39), which extends from the opening (37) for the entry of the accommodating part (43) into the inner filter cavity (23), and which encloses the accommodating part (43) in a sleeve-like fashion.
 15. The filter apparatus according to claim 1, characterized in that the accommodating part is configured in the manner of a spike (43), and in that the accommodating space (39) is configured in the manner of a dome (35).
 16. The filter apparatus according to claim 1, characterized in that the opening (37) of the accommodating dome (35) is delimited by rims around the opening that are adapted to the shape of the cross-section of the part of the spike (43) that fits there-through, and in that said rim defines the part of the side (47) of a square.
 17. The filter apparatus according to claim 1, characterized in that the interior wall of the accommodating dome (35) includes planar surface parts (45) that converge toward the internal end of the accommodating dome and that achieve a fitting contact with the planar surface parts (45) of the spike (43), which is disposed in the accommodating dome (35). 